Preliminary results of a clinical study designed to compare the clinical performance of digital breast tomosynthesis (DBT) versus full-field digital mammography (FFDM) demonstrated superior performance by DBT for conspicuity of findings, according to a group of Italian researchers who presented their findings at the 2008 International Workshop on Digital Mammography (IWDM) this week.
“Results confirmed that lesion conspicuity is improved by moving from 2D imaging (tomography) to 3D through tomosynthesis and the difference was significant for all three radiologists involved in the preliminary study,” wrote the authors of the study conducted at the Oncological Institute of Veneto in Padua, Italy.
An assessment of DBT versus FFDM was performed on the first 50 patients enrolled in a 100 patient study group initiated in April 2007. Patients enrolled in the study had at least one lesion discovered by mammography or ultrasound and classified as suspicious or probably malignant.
All patients underwent an FFDM in two views, cranio-caudal (CC) and medio-lateral-oblique (MLO), and a DBT in one view, MLO. The DBT device used is an investigational prototype developed by GE Healthcare and is based on its standard FFDM Senographe DS device.
The study authors, who presented their results in a scientific poster presentation, stated that the total radiation dose delivered to perform the DBT exam was not higher than the dose required for a standard mammography exam.
Three experienced breast radiologists independently evaluated tomosynthesis and mammography images and rated localized findings in terms of conspicuity, type, and Breast Image and Data Reporting System (BIRADS) category of 1-5. Reconstructed DBT images, which were post-processed with an iterative Simultaneous Algebraic Reconstruction Technique (SART) algorithm, were interpreted on a GE SenoAdvantage workstation with dedicated DBT software.
Readings of the first 50 patients in the study were conducted over several sessions and FFDM and tomosynthesis views of the same patient were excluded as part of the randomization process for each radiologist, the authors noted.
The scientists found that DBT delivered fewer false-negative findings than FFDM in addition to a statistically significant difference in lesion conspicuity for all three radiologists, showing that the technology tends to increase lesion detectability. The research team also reported that DBT improved conspicuity for calcification clusters compared with FFDM.
The authors noted that 2D mammography is limited by tissue overlapping, which can obscure real abnormalities leading to false negatives or can create false suspicious findings that lead to false positive results. The DBT technology allows for the reconstruction and viewing of the whole breast in either 1-mm slices or automatically via cine-mode software capabilities.
The Italian team cautioned that their results, though promising, are preliminary and emphasized that many clinical trials of DBT technology remain to be accomplished.
“Rigorous studies will be necessary to base any assessment about possible differences between tomosynthesis and mammography and to understand the real utility of DBT in routine clinical workflow,” the authors stated.